Romans are staying at home or shielding themselves with umbrellas when venturing out this autumn as the city is bombarded by tonnes of slippery and foul-smelling excrement from millions of migrating starlings.

The problem is an annual one, but this year the cash-strapped city has failed to muster the €40,000 it usually spends on hiring 20 people to walk under plane trees lining the Tiber – where the birds roost en route to Africa – with loudspeakers in order to scare them off with recordings of the screeching noise starlings make when predatory falcons approach.

Without this critical deterrent, the usually manageable problem has become a plague this year, with pavements, benches and monuments unrecognisable under a crust of guano. Roads have become slick with waste, sending scooter riders skidding.

"During their stay in Rome, the birds fly out in the countryside and eat olives off the trees, so their mess becomes oily and more dangerous for mopeds, which have been involved in accidents," said council spokeswoman Raffaella Mercolella.

The loudspeaker-wielding council workers usually head out at dusk, when the birds return from foraging.

"The recordings are efficient, but they usually start in October," said Mercolella, adding that the city's budget was being approved with a "huge delay" due to council elections earlier this year. The €40,000 have now been found, however, and the city will soon be full of the familiar, recorded sound of screeching starlings, to Rome's huge relief.